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  • Author or Editor: W. Reimschüssel x
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Abstract  

Using the technique of liquid scintillation,32P and45Ca activites were determined in biological samples such as bones, blood, milk and egg shells, white and yolk. Samples were mineralized in 70% HClO4 and 30% H2O2 at 70 °C and measured after addition of the “Aquasol” scintillation liquid. A correction for quenching was made by the method of sample channels ratio. High detection efficiencies were obtained, above 80% for45Ca and about 50% for32P in a second measuring channel. Recoveries amounted to 0.95–1.06 for32P and to 0.93–0.98 for45Ca.

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Abstract  

By means of liquid scintillation spectrometry we investigated the counting efficiency of the samples containing toluene solution of scintillator (PPO, butyl-PBD, PT) and 1-methyl[2−14C]imidazolidinone-2 adsorbed on the silicagel, depending on concentration of scintillator, mass of radioactive compound, and mass of another nonactive compound introduced to samples as an impurity. For the sake of comparison the efficiency of counting homogeneous samples and the ones with Ba14CO3 deposit was determined. It was found, that the efficiency of detection of a radioactive compound adsorbed on the silicagel is conditioned by composition of adsorptive layer on the support surface.

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The kinetics of transformations of freshly-prepared amorphous and monoclinic sulphur were determined with a nonisothermal — nonadiabatic calorimeter at 35– 45° and 25–45°, respectively. The experimental data were fitted to the equation of Avrami and the coefficients of the equation were calculated. From the results it was evident that only a process of rhombic sulphur formation proceeds in monoclinic sulphur, while two processes proceed in amorphous sulphur: a rapid one, consisting in the formation of S8 rings from biradical chains, and a slow one, consisting in the formation of rhombic sulphur.

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Abstract  

The differential determination of203Hg and14C or35S in double labelled biological samples is presented. The biological samples were mineralized with 70% HClO4 and 30% H2O2 in minivals MILLI-6. The γ-activity of203Hg was measured on a well scintillation counter. The total activity, due to203Hg and14C or35S, was measured by the liquid scintillation technique after addition of Aquasol into the same vials. The method of external standard channel ratio was used for standardization. Very good recoveries were obtained: 100±0.7% for203Hg and 94.6–101.0% for14C and35S. This method could be used for other β, γ and β-active nuclides with similar β-spectra.

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Abstract  

Phosphorus-32 and chlorine-36 radioactivity was measured directly in commercially available tissue solubilizers using a liquid scintillation counter. Various wavelength-shifting compounds: β-naphthol, 4-methylumbelliferone, 7-amino-1,3-naphtalenedisulfonic acid, 2-hydroxy-3,6-naphthalenedisulfonic acid, anthranilic acid and salicylic acid were investigated to assess their suitability for the improvement of counting efficiency. Salicylic acid was selected which is fairly stable in alkaline solutions of tissue solubilizers and remarkably improves counting efficiency up to 90% for both nuclides. 0.1 g of soft tissues or blood can be solubilized with 1 cm3 of tissue solubilizer containing 2 g/dm3 of salicylic acid directly in 6 cm3 scintillation minivials. The sample channels ratio method for colour quench correction was found to be satisfactory.

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